1. Field of the Invention
The present invention relates to a positive photosensitive resin composition and a method of forming a cured film from the same. More particularly, the present invention relates to a positive photosensitive resin composition that can be appropriately used in the formation of a planarizing film, protective film or interlayer insulating film for electronic components, such as a liquid crystal display device, an integrated circuit device, a solid-state image sensor and an organic EL, and relates to a method of forming a cured film from the same.
2. Description of the Related Art
In the field of electronic components, such as a liquid crystal display device, an integrated circuit device, a solid-state image sensor and an organic EL, it is of conventional general practice to use a photosensitive resin composition in the formation of a planarizing film for planarizing the surface of electronic components, a protective film for preventing the deterioration and damaging of electronic components or an interlayer insulating film for maintaining the insulation of electronic components. For example, a TFT liquid crystal display device is manufactured in the following manner. First, a polarizing sheet is disposed on a glass substrate, and a transparent conductive circuit layer of ITO or the like and a thin-film transistor (TFT) are formed thereon. Further, the thus obtained laminate is coated with an interlayer insulating film, thereby obtaining a back plate. Separately, a polarizing sheet is disposed on a glass substrate, and according to necessity patterns of black matrix layer and color filter layer are formed thereon. Further, a transparent conductive circuit layer and an interlayer insulating film are sequentially provided thereon, thereby obtaining a top plate. The back plate and the top plate are arranged opposite to each other with a spacer therebetween, and a liquid crystal is sealed in the interspace of the plates, thereby obtaining a TFT liquid crystal display device. In this process, a photosensitive resin composition is used in the formation of the interlayer insulating films. It is required for such a photosensitive resin composition to excel in the sensitivity, film retention ratio, heat resistance, adherence and transparency. Further, it is required for the photosensitive resin composition to excel in the aging stability during storage.
With respect to such a photosensitive resin composition, for example, patent reference 1 proposes a photosensitive resin composition which comprises (A) a resin soluble in alkali aqueous solutions that is a polymer of (a) an unsaturated carboxylic acid or unsaturated carboxylic anhydride, (b) a radical-polymerizable compound containing an epoxy group and (c) another radical-polymerizable compound and (B) a radiation-sensitive acid generating compound. Patent reference 2 proposes a photosensitive resin composition which comprises an alkali-soluble acrylic polymer binder, a compound containing a quinone diazide group, a crosslinking agent and a photoacid generator. However, both of these photosensitive resin compositions are not satisfactory in the sensitivity, film retention ratio in unexposed areas, resolution and aging stability, so that they have been unsatisfactory from the viewpoint of manufacturing a liquid crystal display device of high quality. Moreover, patent reference 3 proposes a positive chemically amplifiable resist composition comprising a crosslinking agent, an acid generator and a resin that is itself insoluble or sparingly soluble in an alkali aqueous solution but has a protective group cleavable by the action of an acid and that once the protective group is cleaved, becomes soluble in an alkali aqueous solution. However, this resist composition is not satisfactory in the adherence and transmission, so that it has been unsatisfactory from the viewpoint of manufacturing a liquid crystal display device of high quality. Patent reference 4 proposes a radiation-sensitive resin composition comprising a resin of acetal structure and/or ketal structure containing an epoxy group and an acid generator. However, the composition has poor sensitivity, rendering the composition unsatisfactory.
[Patent reference 1] Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) H5-165214,
[Patent reference 2] JP-A-H10-153854,
[Patent reference 3] JP-A-2004-4669, and
[Patent reference 4] JP-A-2004-264623.